The NFT marketplace that showcases the 1 of 1, only and always. Cleaner. More reserved palette in every way as far as their UX goes. The barrier to entry is much steeper than OpenSea or Rarible. One must fill out a Google Docs application including various links to your art's web presence, an application video, the story behind the work you'd like to post on their site, and access to some sort of cloud storage to view a sample of your work.
Their community tab is full of short forum-like answers that seems to play off as a FAQ page.
The range of bids here is steeper than the other two as well, being that the demographic is peak exclusivity, with only one issuance of anything in the marketplace, many pieces achieve a four-figure price handle, with a handful of pieces exceeding low six-figures.
Unlike the other two previously mentioned exchanges, SuperRare takes the notion of an NFT literally for the art community, paying no attention to more abstract utilities of smart contracts. High Digital Art, or at least, exclusively digital art is their demographic.
Compared to Rarible and OpenSea, just logging into their site with your MetaMask wallet will require a GAS fee (as of now, it stands at over $45 USD)